Many commentators argued that this was hard to believe when Afghanistan and Iraq were having some of their worst months of violence, Somalia and Sudan continued to be riven by pitiless civil war and Syria, Yemen, Bahrain and Libya were erupting.But what Obama said happens to be true. Quite a number of readers thought my last column arguing that war was diminishing had exaggerated the argument but I hadn’t. Now I can add even more evidence thanks to the work of Professor Goldstein of American University, author of “War on War: The Decline of Armed Conflict Worldwide”. He reminds us that 10 years ago former Secretary of Defence, Robert McNamara, architect of the blanket bombing of North Vietnam, who later became a penitent peacenik, estimated that we could look forward in this century to an average of three million deaths a year.

In fact the last decade, the post 9/11 decade, has seen fewer war deaths than any decade in the past 100 years. Today they are half what they were in the 1990s and a third of what they were during the Cold War years. Terrible though 9/11 was, it barely registers compared with the siege of Leningrad, the battle of the Somme or Vietnam.

One thing has certainly changed. We didn’t know much about either the Somme or Leningrad, merely the bare bones of events, until months afterwards. Now we get war reporting in real time—either from reporters on the ground with their satellite communications or, as in the case of Syria, from the mobile phones of locals. Thus we feel ourselves caught up in endless conflicts. But it is an illusion. There have been no interstate wars for some time and the number of civil and ethnic wars has fallen steadily almost every year of the last twenty. There are about a quarter fewer than in 1990 and the last sustained territorial war between two regular armies was between Ethiopia and Eritrea, which ended a decade ago. America may spend as much on defence as all the other countries in the world combined and can be seen as a strutting giant but, judging from the number of battle deaths, the severity of conflicts it is engaged in has fallen dramatically and once it withdraws from Iraq this year and from Afghanistan in 2014, as Obama says it will, the numbers will go down again. By then the US will have fewer troops deployed around the world than at any time since the 1930s. Over the last decade 6,000 US armed forces’ members have been killed. Compare this with 58,000 in Vietnam and 300,000 in World War II or, if you like, with the number of Americans who died falling out of bed—last year there was a higher death toll than in all America’s wars combined.

The attitude to civilian deaths in recent years has undergone a scene change- not just since Vietnam when the US military seemed not to care what its bombs were doing but also since the early days of Iraq when the US and its allies hammered civilians and soldiers alike. The war in Afghanistan began a decade ago totally careless of civilian life but last year when a NATO air strike hit a house in Marja district killing nine civilians the senior NATO commander apologised to President Hamid Karzai.

It is reported that NATO air attacks on Libya have killed less than two-dozen civilians. At last the penny is beginning to drop among the generals and their political masters that a 50/50 ratio between military and civilian deaths, which was the norm for centuries is totally counterproductive. It sets the populace against the aggressor.

What will the future bring? After all we have had peaceful times before, in Europe for the best part of a hundred years before World War 1. All one can say is that the prospects for peace are good. China hasn’t fired a single shot in battle for 25 years. Americans get tired of their wars more and more quickly. In Africa the number of wars has fallen fast as most of the continent engages for the first time in the serious business of economic growth and making democracy work. Europeans are far less likely than they were in 1914 to let their leaders manipulate them and are much less prone to act on distorting calls for honour and patriotism.

The historical evidence is now overwhelming — we live in a world with an unprecedented small amount of war. Diminishing it even further is the next task. We all have to work at it but as with waging war, Americans have the biggest task — to make sure no Bush-like Republican enters the White House.

Jonathan Power is a veteran foreign affairs commentator based in London